Ch. 11 Flashcards
1
Q
- The control loop is made up of four basic functional blocks:
1) Process
2) Process Variable
3) Measurement
4) Automatic controller
5) The final control element
a. 1, 3, 4, 5
b. 3, 4
c. 1, 2, 3
d. 1, 2, 3, 4, 5
A
a. 1, 3, 4, 5
2
Q
- For purposes of control theory, a process can be defined as an action in which material and/or ________ is modified to a different form.
a. fluids
b. energy
c. gas
d. oil
A
b. energy
3
Q
- Process parameters such as temperature, pressure, and flow require continuous measurements in real time. If review of the measurements is desired, provision must be made to capture the parameters with respect to time.
a. True
b. False
A
a. True
3
Q
- Flow rate is often measured with a _________________.
a. pedometer
b. ultrasonic meter
c. orifice plate
d. velocity meter
A
c. orifice plate
4
Q
- List the four types of final actuators:
1) Conveyor belt
2) Flapper valve
3) Globe valve
4) A louver
5) Motor’s variable speed drive
6) A compressor’s inlet guide vanes
a. 1, 2, 3, 4, 5, 6
b. 1, 6
c. 4, 5, 6
d. 1, 4, 5, 6
A
d. 1, 4, 5, 6
5
Q
- Pneumatic systems can operate on:
1) Compressed air
2) Hydraulic fluid
3) Nitrogen
4) Water
5) Methane
a. 1, 2, 3, 4, 5
b. 1, 3, 5
c. 1, 5
d. 1, 2, 5
A
b. 1, 3, 5
5
Q
- Transmitters convert a process physical quantity such as level, pressure, flow, or temperature into a representative pneumatic analog signal, usually ________.
a. 0 - 25 kpa
b. 20 - 100 kPa
c. 4 - 20 mA
d. 1 - 100 %
A
b. 20 - 100 kPa
6
Q
- Control valves are responsible for providing process changes by manipulating fluid flow in a pipeline. They are called a “Primary Control Element” (PCE), as they are the final devices that the controller uses to affect corrective action to the process.
a. True
b. False
A
b. False
7
Q
- List the three main elements of an Analog Instrumentation Loop.
1) Process setpoint
2) Transmitter
3) Controller
4) Instrument air
5) Final control element
a. 1, 2, 3, 4, 5
b. 2, 3, 5
c. 1, 3, 4,
d. 1, 2, 3, 4, 5
A
b. 2, 3, 5
7
Q
- Pneumatic switches are available for:
1) Level
2) Pressure
3) Viscosity
4) Temperature
5) Density
6) Flow
a. 1
b. 1, 2, 3
c. 1, 4, 5, 6
d. 1, 2, 4, 6
A
d. 1, 2, 4, 6
8
Q
- __________ are used to convert physical quantities of flow, level, temperature, pressure, and weight into electrical signals that represent those quantities as accurately as possible.
a. Controllers
b. Control valves
c. Transmitters
d. Level switches
A
c. Transmitters
9
Q
- The controller uses an operational amplifier to perform a mathematical summation, in order to compare the input signal (process variable) with a setpoint that is established by operations personnel. If the process is not at the set value, the mathematical functions present in the controller will produce an output signal that will correct the process.
a. True
b. False
A
a. True
9
Q
- Square root extractors are used to convert squared signals from _______ flowmeters to ______ flow signals.
a. digital, analog
b. differential, linear
c. normal, normal
d. steam, boiler feedwater
A
b. differential, linear
10
Q
- The main devices used as final control elements are:
1) Control valves
2) Variable speed motor drives (VSDs)
3) Steam flow
4) Speed governors
5) Level switches
6) Damper positioners
a. 1, 6
b. 4, 5, 6
c. 1, 2, 6
d. 1, 2, 4, 6
A
d. 1, 2, 4, 6
10
Q
- A typical controller station allows the operator to:
1) View and change the setpoint
2) View feed forward settings
3) View the process variable
4) Switch from Auto to manual
5) View process history
a. 1, 2, 3, 4
b. 1, 2, 3, 4, 5
c. 1, 3, 5
d. 1, 2
A
c. 1, 3, 5
11
Q
- Large control rooms almost invariably contain a number of video ________ consoles attached to a large distributed control system data highway.
a. game
b. display
c. operator
d. digital
A
c. operator
11
Q
- The term “digital” describes computer systems that use the binary number system of _____ and _____.
a. zeros, tens
b. ones, zeros
c. tens, one hundreds
d. disc, hard drives
A
b. ones, zeros
12
Q
- Smart transmitters transmit process information in either a digital or the 4 - 20 milliamp analog format. They can be re-zeroed and rearranged remotely, using a hand-held calibrator.
a. True
b. False
A
a. True
13
Q
- The smart transmitter is really a digital device, containing an on-board ___________ complete with memory.
a. microprocessor
b. calibrator
c. video
d. process variable
A
a. microprocessor
13
Q
- In on-off control, the controller signal to the final control element is either ____ positive or ______ negative.
a. 0 %, 100 %
b. 0 %, 50 %
c. 100 %, 100 %
d. 100 %, 24 %
A
c. 100 %, 100 %
14
Q
- The majority of final control elements are, and will continue to be ____________________.
a. control valves
b. microprocessors
c. hand held computers
d. globe valves
A
a. control valves
15
Q
- The percent of the process variable range that causes _____ change in controller output is often called the proportional band.
a. 25%
b. 100%
c. 20%
d. 75%
A
b. 100%
16
Q
- The difference between the set point and the actual value of the process variable is known as offset. Offset is an inherent characteristic of all reset only controllers.
a. True
b. False
A
b. False
16
Q
- Most common three examples of on-off control are:
1) Temperature controlled exhaust fan in a compressor building
2) Boiler feedwater to a boiler
3) A thermostat controlled forced air furnace
4) Boiler fuel gas flow
5) The compressed air supply to a storage tank
a. 1, 2, 5
b. 1, 3, 5
c. 3, 4, 5
d. 4, 5, 6
A
b. 1, 3, 5
17
Q
- Integral control, often called reset, responds to both the _______ and ______ duration of the deviation.
a. offset, span
b. speed, magnitude
c. amount, time
d. error, reset
A
c. amount, time
17
Q
- Reset on integral time can be varied by manipulating the integral adjustment valve.
a. True
b. False
A
a. True
18
Q
- The difference between feedback and feedforward control is apparent. Feedback control works to eliminate errors, whereas feedforward control operates to prevent errors from occurring in the first place.
a. True
b. False
A
a. True
18
Q
- In a closed-loop control configuration, a measurement is made of the controlled variable, and this is compared with the desired ______ or ____ .
a. output, signal
b. value, setpoint
c. PV, SP
d. Product, material
A
b. value, setpoint
19
Q
- Cascade control is achieved by the use of two controllers, but only one _________.
a. SP
b. PV
c. OP
d. final control element
A
d. final control element
19
Q
- The difference between feedback and feedforward in a controller is; Feedback control works to eliminate errors, where feedforward control operates to prevent errors from occurring in the first place.
a. True
b. False
A
a. True
20
Q
- Ratio control is often associated with process operations when it is necessary to continuously mix two or more streams together in order to maintain steady composition of the resulting mixture.
a. True
b. False
A
a. True
20
Q
- The Auto-Select loop control allows the automatic selection between one or more measured or controlled variables to produce a _______ output that is used as a controlled variable.
a. double
b. single
c. triple
d. strong
A
b. single
21
Q
- Emergency Shutdown (ESD) devices are operated by ___________________.
a. air & hydraulics
b. hydraulics, electricity and air
c. air, hydraulics, electricity or combinations of all three
A
c. air, hydraulics, electricity or combinations of all three
21
Q
- Loop alarms are devices that signal the existence of an abnormal condition by means of an audible or visible discrete change, or both, intended to attract attention
a. True
b. False
A
a. True
22
Q
- The two most common reasons to active an ESD’s are: 1. Shutdown and isolate rotating equipment 2. Shutdown and depressure
a. True
b. False
A
a. True
23
Q
- An emergency shutdown could be activated __________ or __________.
a. locally, remotely
b. fast, slow
c. automatically, manually
d. full, partial
A
c. automatically, manually
